1. Field of the Invention
The invention herein relates to valves and connectors, such as those use in medical liquid flow applications such as intravenous (IV) administration of medications. More particularly it relates to needleless valves for such applications.
2. Description of the Prior Art
There are many instances, particularly in the medical field, where quantities of liquid must be moved from a source of the liquid to a liquid conduit system under restricted and usually sterile conditions. A principal example is the administration of medication or other liquids to a patient intravenously. When the intravenous administration is to be conducted at periodic intervals over a extended period of time, the conventional practice is to insert a catheter into the patient""s vein, usually through the patient""s forearm, and leave the catheter in place with a portion extending out of the patient""s arm and terminating in a valve (receiver) for periodic connection to the liquid source as required. The presence of the valve avoids the necessity of using direct injection of the patient each time the medication is to be administered, which would be both painful to the patient and also increase the risk of infection each time the skin was penetrated.
For many years, receivers of valves were constructed with a resealable membrane, such as a rubber or other elastomeric plug, stretched across the inlet end of the device, closing off the IV fluid conduit. When it was time to administer medication or other fluid, the physician or nurse would use a conventional hypodermic syringe with a sterile hypodermic needle which would penetrate the rubber plug and allow sterile injection of the fluid in the syringe directly into the liquid conduit or cannula. Upon withdrawal of the hypodermic needle, the elastic rubber plug would resile and seal itself, maintaining the sterile condition of the interior of the system.
Such practice, however, has numerous disadvantages. Repeated piercing of the plug with the hypodermic needles eventually damages the plug sufficiently that it cannot maintain the appropriate sterile seal. Further, since the valve/receiver devices are normally quite small, the plug is even smaller, often less than xc2xc inch (6 mm) in diameter. Therefore the person administering the medication had to take care in manipulating the syringe so that the hypodermic needle would pierce the rubber plug and not hit the other portions of the receiver, the patient""s arm, or even the hands or arms of the person himself or herself. To take the appropriate amount of care, of course, required some period of time, thus reducing the number of patients a physician or nurse could serve in a given time period. In addition, it was not uncommon for hypodermic needles to break off in the plug during or before administration of the liquid, thus usually becoming lodged in the rubber plug and requiring the administrator to take time to remove the broken needle. Further, such breakage also commonly caused the loss of all or a portion of the medication or other liquid in the syringe and, of course, not properly administered to the patient.
Such problems were particularly common in situations where the medical personnel were required to act very rapidly, such as in emergency room and emergency medical administration settings.
The accidental piercing of the skin of the doctor or nurse raised critical problems. If such occurred before administration of the medication to the patient, the medication, or at least a portion of it, was injected into the nurse or doctor, which not only deprived the patient of the medication, but in fact might be quite harmful to the physician or nurse. If the accident occurred after administration of the fluid to the patient, the hypodermic needle could easily be contaminated by the patient""s blood or other bodily fluid, thus being capable of transmitting the patient""s disease to the physician or nurse. While this was a severe problem at any time, it became a truly critical problem as various highly infectious or virulent diseases became more prevalent in the population. The added presence of infectious diseases with extremely high rates of mortality among patients, such as AIDS, gave priority to development of devices which would eliminate the need for use of hypodermic needles.
In more recent years, xe2x80x9cneedlelessxe2x80x9d connectors and receptors have been developed and widely marketed. In systems using this type of device, the fluid dispenser (usually a syringe) is fitted with a blunt nozzle rather than a hypodermic needle. The blunt nozzle is designed to be received into a corresponding receiver attached to the IV line or other fluid conduit. Within the receiver is normally a hollow tubular cannula, which is a fixed member forming the extended end of the fluid conduit extending into the patient""s veins. Sterility of the receivers is important so that transfer of the liquid from the syringe to the cannula and IV fluid conduit can be conducted under sterile conditions.
While the xe2x80x9cneedlelessxe2x80x9d concept has been well known and is quite simple, implementation of the concept in practice has been quite difficult. Needleless connectors have, for the most part, been designed with a hollow flexible plug which fits over the cannula and which has a self-sealing slit or similar closeable opening in its exterior end. The interior end of the plug is anchored adjacent to the downstream end of the cannula (i.e. the end leading into the IV system and the patient""s arm). Since the cannula is made as a rigid elongated tube, as the nozzle of the fluid dispensing device is pushed into the receiver, it contacts that exterior end of the rubber plug and forces that end inwardly against the distal end of the cannula. The distal end of the cannula contacts the slit at the end of the plug and forces the slit open, so that the plug then becomes a sleeve as it is pushed inwardly along the outer surface of the cannula. Eventually, the distal end of the cannula, now being exposed, contacts the interior fluid transfer tube of the dispensing device as the nozzle of the dispensing device moves further into the receiver. When this connection is made, the fluid can be transferred from the syringe directly into the cannula through which it flows onto the IV system in the patient""s body. Such opening of the device is commonly referred to as xe2x80x9cactivationxe2x80x9d of the xe2x80x9cvalve.xe2x80x9d
Once the fluid is fully transferred, the nozzle of the dispensing device is withdrawn outwardly through the receiver, causing the flexible plug to resile and extend distally along the cannula until it passes the cannula end and returns to its xe2x80x9cdeactivatedxe2x80x9d position enclosing the end of the cannula with the slit again sealed. Examples of devices of this type are shown in U.S. Pat. No. 5,065,783 (Ogle) and U.S. Pat. No. 5,549,577 (Siegel et al.) and in published PCT application no. WO 93/11828 (Lopez).
While such devices have worked well for the most part, they have been found to have some serious deficiencies. One of the most important is the fact that upon deactivation and withdrawal of the nozzle of the syringe or other fluid dispensing device, the compressed plug resiles back to its original position, thus increasing its internal volume back to its deactivated volume, thus creating a partial vacuum in the cannula and attached catheter. This produces a suctioning effect which often causes the patient""s venous blood to be drawn into the catheter where it remains and can clot, thus preventing flow through the catheter. When it comes time to administer the next fluid dose, the plugged catheter prevents administration of the fluid. Remedying of the problem requires that the catheter be cleaned or replaced. This, of course, is a major problem in emergency situations, whether in an emergency room or when a patient on IV suffers some sort of relapse or seizure or other critical condition and medication must be administered through the IV without delay. Even in the absence of an emergency, however, withdrawal of the device for cleaning of the catheter requires that the IV subsequently be reinserted into the patient. In ordinary situations this at least requires the time of a nurse and is a discomfort for the patient. In many cases, however, reinsertion is a problem that requires a doctor""s intervention, as for instance where an new acceptable insertion site is difficult to find or the patient does not tolerate needle insertions well. Thus reinsertion presents a significant cost event for the medical team and subsequently for the patient.
Other forms of connectors in needleless couplings have been described. These may have components within the coupling intended to hold the fluid flow conduit open against the tendency of flexible sleeves attached to one or the other end of a coupled tubing to compress and close the fluid flow path. A typical example is shown in U.S. Pat. No. 4,457,749 (Bellotti et al.) in which a xe2x80x9cspikexe2x80x9d having a cruciform cross section is used to hold open a fluid path within the coupling as the two portions of the tubing are joined together.
I have now invented a needless valve which avoids the suctioning problems of the prior needleless devices and which, in fact, can be structured to provide a positive self-purging effect upon deactivation. This device retains all of the favorable aspects of the needleless valve system for activation and administering the medication to the patient, but avoids all of the detrimental effects of the prior art devices that occur during deactivation. The present device is virtually impossible to clog, is self-purging at the end of an administration cycle, and helps ensure that substantially all of the medication dispensed from the syringe is administered into the patient. The device is also extremely simple in design and easy to construct and assemble, since it consists of only three pieces. The device may be made in a variety of different configurations, all of which provide the same self-purging action and clear flow path for the administered liquid.
The device of this invention is configured so that a core rod forces the plug to expand during activation in a manner not possible with the prior art devices, which causes the interior volume of the plug to increase substantially from its rest (deactivated) volume and opens a flow path through the valve for the administered fluid. Upon deactivation, the plug resiles and its interior volume returns to rest volume, closing the fluid flow path and displacing residual fluid within the valve, so that the residual fluid is expelled from the valve through its outlet into the downstream conduit or unit, purging the valve and promoting use of all of the administered fluid. In addition, such volume decrease prevents occurrence of any partial vacuum in the valve, and in fact usually creates a transient overpressure, which also assists in purging the valve of residual fluid. The structure thus maintains either a positive or neutral (i.e., non-negative) pressure at all times, preventing any suctioning of blood from a patient into an attached catheter, thus avoiding clogging of the catheter by formation of clots in blood drawn into it.
In a broad embodiment, the invention involves a needleless valve comprising a tubular housing having a fluid inlet end and a fluid outlet end, a solid rod within the housing, and a hollow flexible plug within the housing and moveable along the rod, the hollow plug in response to insertion of a fluid supply nozzle into the inlet end moving in one direction along and cooperating with the rod to increase the volume of the interior of the plug and open a fluid flow path between the inlet and outlet ends, and in response to withdrawal of the fluid supply nozzle from the inlet end moving in an opposite direction along and cooperating with the rod to decrease the volume of the plug interior, close the fluid flow path between the inlet and outlet ends and cause residual fluid in the flow path to be expelled from the valve through the outlet end.
In another broad embodiments, the invention involves a needleless valve having a distal end and a proximal end, and comprising a base disposed at the proximal end and comprising a connector for fluid communication attachment to a fluid flow tube, a solid elongated fluid channeling rod extending from a proximal end joined to the base to a distal end, and a fluid flow conduit formed in the base and extending through the connector into the proximal end the rod and disposed for the fluid communication with the tube; a flexible plug having a wall forming a hollow interior bounded by an inward facing surface; the plug fitting over the rod, being sealingly attached to the base and being moveable along the rod between a first activated position and a second deactivated position; in the first activated position the rod maintaining the plug in a form with the interior having a first larger volume, with the plug withdrawn from the distal end of the rod, and creating a fluid flow path through the interior and along the rod; and in the second deactivated position the plug being in a form with the interior having a second smaller volume with the distal end of the rod covered by the plug and the fluid flow path being blocked by the wall of the plug; and a tubular housing fitting over the plug and extending from the distal end of the device to the base, at the distal end the housing having an elongated receiver for releasable fluid communication reception of a nozzle of a fluid source, the receiver configured to guide movement of the nozzle along the receiver into contact with the plug, the plug moving between the first and the second positions in response to movement of and contact from the nozzle; such that movement of the plug from the first position to the second position in response to insertion of the nozzle into the receiver causing the rod and the plug to cooperate to expand the plug and increase the interior volume and open the valve to fluid flow between the source and the tube, and subsequent movement of the plug from the second position to the first position in response to withdrawal of the nozzle from the receiver causing the plug to resile and the interior volume to decrease, closing the valve to the fluid flow, displacing residual fluid within the valve and causing the residual fluid to flow from the proximal end of the valve into the tube.
In another embodiment the invention also comprises a rod for a needleless valve comprising a solid elongated core having a plurality of coaxial ribs extending outwardly therefrom.
Ribs made be made with a uniform width so that their extended edges are straight, with continuously varying widths so that their edged form straight or curved smooth tapers, or have discontinuously varying widths, so that their edges form one or more steps over the length of each rib. In one embodiment, the ribs terminate at the distal end of the rod in a hollow annular member encircling the rod.
Additional features of the invention as well as descriptions of the various forms of the components will be set forth below.